1. Field of the Invention
The invention relates to a cassette clamp for a microtome.
2. Description of the Related Art
Before specimens can be cut using a microtome, the specimens must be made stable. To do this, they are embedded in paraffin, for example. This embedding in paraffin is usually done in so-called plastic cassettes, as are described in DE-43 33 118-A1, for example. To cut them, the embedded specimens are placed, together with the cassettes, in the clamp of a microtome.
A clamp which can hold cassettes of this type is known from U.S. Pat. No. 3,802,691. The clamp has a base part with fixed limit stops and forms, together with a movable clamping jaw, a holder for a cassette. Compression springs are provided between the clamping jaw and the base part. The first end of a pivotally mounted tie rod is connected to the clamping jaw via a thread, while its other end is connected to an eccentric. The clamping jaw can be adjusted slightly via the thread of the tie rod, so that the holder can be adapted to different cassette sizes.
A similarly constructed specimen clamp for a microtome is known from DE-36 07 766-C1. In this clamp, the tie rod is designed as a spindle on which the movable clamping jaw runs for the purpose of adjusting the holder size. In this case, the specimen is also clamped via an eccentric.
A quick-action chuck system for microtomes with a chuck head is known from DE-30 40 217-C2, in which the specimen can be clamped between four fingers forming a holder. The fingers are secured with cam followers, which are connected to one another by springs. The holder can be opened and closed via a pivot lever for the purpose of receiving the specimen.
A cassette clamp for a microtome is known, for example, from the publication "LEICA RM 2145" from Leica Instruments GmbH, July 1997. The cassette clamp has a base part with fixed limit stops as a support for the paraffin cassette. Provided opposite these limit stops there is a clamping jaw which is mounted on the base part so as to pivot about an axis. The clamping jaw is pre-stressed via a tension spring and thus presses against the inserted cassette. Also arranged on the clamping jaw there is a lever via which the clamping jaw can be moved about its pivot axis into a cassette-exchange position counter to the spring force.
In these known cassette clamps, two hands are needed to change cassettes. One hand is used to move the lever into the cassette-exchange position and to hold it there counter to the spring force. The cassette is then either removed or inserted using the other hand. When holding the lever in the cassette-exchange position, force has to be applied, so that there is a danger of slipping and injuring oneself on the cutting knife.